PURPOSE: To allow a mass to work with full damping effect and provide good shutting-off by furnishing a retaining member to retain the mass with movability for a certain distance, and providing an air chamber for application of a certain specified air pressure.

CONSTITUTION: An equilibrium chamber 64 is put in communication with a pressure receiving chamber 38 through a throttle passage 72 of a partitioning member 26. Input vibration is damped well on the basis of the liquid column resonance effect of a non-compressive fluid flowing through the throttle passage 72. An air pressure adjusting circuit 76 is connected with an air chamber 52 of a pneumatic spring mechanism. The air pressure in this air chamber 52 is changed according to the driving condition of the car. The frequency range of vibration is changed on the basis of resonance of a metal block 36. Thus the device can work with good shut-off effect while exerting the damping effect.